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SubjectRe: [Xen-devel] [PATCH] [v2] xen: hypercall: fix out-of-bounds memcpy
On Mon, Feb 5, 2018 at 4:14 PM, Jan Beulich <JBeulich@suse.com> wrote:
>>>> On 05.02.18 at 16:03, <arnd@arndb.de> wrote:
>> int xen_event_channel_op_compat(int cmd, void *arg)
>> {
>> - struct evtchn_op op;
>> + struct evtchn_op op = { .cmd = cmd, };
>> + size_t len;
>> int rc;
>>
>> - op.cmd = cmd;
>> - memcpy(&op.u, arg, sizeof(op.u));
>> - rc = _hypercall1(int, event_channel_op_compat, &op);
>> -
>> - switch (cmd) {
>> - case EVTCHNOP_close:
>> - case EVTCHNOP_send:
>> - case EVTCHNOP_bind_vcpu:
>> - case EVTCHNOP_unmask:
>> - /* no output */
>> - break;
>> + if (cmd > ARRAY_SIZE(evtchnop_len))
>> + return -ENOSYS;
>
>>= perhaps?

Argh, of course. This is why I preferred the switch/case version, I knew
I'd screw this up somehow ;-)

Arnd

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